Form 3895 Part II, Column A & Column B are zeros and Column C has a value. The diagnostic “Household information requires an entry for Monthly Premium in any period where there are entries for Monthly Second Lowest Cost Silver Plan (SLCSP) and or Monthly Advance Payment of Premium Assistance Subsidy.
Did you fully complete the appropriate sections of Screen 39? Are you working from a CA 3895 or a 1095-A? Maybe https://proconnect.intuit.com/community/form-1095/help/how-to-enter-california-health-coverage-in-la... will help.